Those trap doors in the spoiler/bumper on my '90 765T seem like a good entry for a cold air induction ram-air system. Any thoughts? They are not THAT big, actually. Thanks for any help!

this is a stupid question but where is the intercooler located on a volvo turbo? is there a good supply of air being flowed over the intercooler fins? if not, you'd probably get a better performance boost from doing that.

i fail to see what use you would really get out of a ram air intake for your engine unless it so happens that the bottleneck is your intake, which from my understanding i believe is almost never the case without significant modifications to the engine.
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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

the intercooler is in front of the radiator, behind the aircon cooler (if fitted)...

i suspect that there is a LOT of turbulance down there...and god help you if you injest stones, birds or small fury things...

these ideas need thinking about, to tell a story, there was a craze for removing airboxes and filters from 4 cylinder motorbikes some time ago (the carbs sitting behind the engine...) and replaceing them with trumpets directly mounted behind the carbs - more air flow, therefore more power........set the engine up, balance the carbs, check mixtures etc etc..take the bike out and it goes SLOWER...look at the plugs...carbs look out of balance

the reason was that the behaviour at speed of the air flow meant a LOW presure zone behind the block where the inner carbs were...leading to different balances at different speads - which used to be taken care of by the air box...and intakes in very carefully thought out places..

basically what im saying is volvo spent millions designing a car for performance and durability..they probably knew what they were doing, and to be honest I seriously doubt that unless you have SUBSTANTIAL modifications to the engine a ram air intake will make much difference..probably better to buy better quality petrol and replace your plugs more often...

I did see a article (on turbo bricks I think) where a guy had measured the losses in the turbo piping and decided the biggest loss was in the screens on the AMM..he suggested removing the down stream screen i seem to remember...

I'll bet that someone will suggest that Volvo spent quite a bit of time and effort to get a good supply of air to your engine, and sometimes it should be warm.

BUT, it is nice to see a guy who is willing to experiment with his beloved brick.

The trap doors are not really THAT small when you consider that you see drag racing bricks that take in air through one of the headlight frames. I think one side would do.

FLASH!!! - The cold air intake on my '96 855R is only 1-1/2 x 3 inches!!!

You could make the intake act like it is bigger by getting something like one of those square tapered outdoor siren or speaker horns that has a mouth that is bigger than the trap door. Stick it in the hole and cut it off about an inch behind the spoiler so you have some material to attach the hose to. If you are really willing to experiment, maybe you could get an appropriately-sized bell from a musical instrument and square it a bit. Or you could make a rectangular cone for the intake.

Try to make the inside of the hose as smooth as possible to reduce turbulance, and as short as you can to reduce friction loss.

How are you going to filter the air? Personally I do not think that a K & N filters clean the air well enough, but they are supposed to flow more air, and they are certainly far better than nothing.

The biggest issue, I think, is to make sure that the air at the trap door is at some pressure higher than atmospheric pressure, and not acting as some type of vacume, hurting performance.

You could fashion a coat hanger wire bracket to hold several pieces of brightly colored yarn in front of the trap door. I would hold a row of 3" pieces of yarn about 1" in front of the hole. Have someone in a "chase" car watch the yarn at various speeds. The ideal result would have the yarn blow straight into the hole. If the yarn flies all over the place, you have turbulance, If the yarn faces forward or off to the sides, top , or bottom, you have a bad flow or vacume. A lot of good streamlining was developed using yarn. Try taping a few pieces at various places on your car and watch it fly.

BTW - the cold air intake on that R is in front of the radiator, mid-way between thr grille and the radiator in the uppet left corner, its opening faces DOWN, probably to get some air pressure trapped in front of the radiator. It probably keeps some big bug or small rock from taking a trip to the turbo!

Good luck and let us know how you make out. A lot of great stuff was discovered by tinkerers like you!


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3 8s & 2 7s 740,000 miles total

Does it rain or snow where you live? Hit a puddle and hydrolock your engine.